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A large-area, conductive, and flexible membrane made from the stabilized aqueous solution of reduced graphene oxide (RGO) is successfully fabricated using an electrophoretic deposition (EPD) method. A low-voltage operation of EPD (∼3 volts) allows a robust consolidation of RGO layers desirably aligned in the in-plane direction through the cohesive electrophoretic squeezing force near the current collector. Transferring the deposited RGO layers to arbitrary substrates or achieving as a free-standing form, two methods of "chemical etching" and "electrochemical etching" are developed to detach the RGO layers from the EPD current collector without damaging the deposited RGO. Further reducing the free-standing RGO membrane by thermal annealing up to 1000 °C, a graphite-like architecture is restored (d-spacing at 3.42 Å with C/O ratio at 16.66) and the electrical conductivity increases as high as 5.51 × 10(5) S/m. The tightly-consolidated and securely-detached RGO membrane allows the free-standing and flexible features and highly conductive characteristics, which are further developed during thermal treatment. Because of the facile scale-up nature of the EPD process and RGO solution, the developed methodology has a considerable potential to be applied to various energy storage devices, flexible conductive coatings, and other electrochemical systems.

Although the graphene-based materials have a great potential to be used for various energy storage devices, the expected performance of graphene has not been achieved yet seemingly due to the lack of interconnected porosity and actively-exposed surface area that should be developed in the re-stacked graphene electrodes. Herein we used an electrophoretic deposition (EPD) method to fabricate a binderfree porous supercapacitor electrode composed of reduced graphene oxide (RGO) sheets and conductive carbon black (CB) particles. Applying EPD for an electrostatically-stabilized aqueous mixture of RGO and CB nanoparticles, the electrophoretic squeezing force in EPD induced the RGO sheets to align in the in-plane direction along with the CB particles placed in the interlayers of RGO. The developed ladder-like interleaved composite structure allowed a desirable porosity network and conductive path for a facile movement of ions and electrons. Controlling the ratios of concentrations (C s,RGO /C s,CB ) and/or zeta potentials (x RGO /x CB ) of the RGO and CB nanoparticles in aqueous mixtures, different nanostructures of the interleaved RGO/CB laminates could be fabricated. Thoroughly tested as a supercapacitor electrode in an organic electrolyte (TEA BF 4 ), the developed RGO/CB electrodes provided excellent performance of the specific capacitance of 218 F g À1 at a scan rate of 1 mV s À1 (133.3 F g À1 at a current density of 2 A g À1 ), energy density of 43.6 W h kg À1 and power density of 71.3 kW kg À1 .It is believed that an ideal performance of intrinsic graphene properties could be exerted by the unique nanostructure of binder-free interleaved graphene laminates as developed by the scalable in situ EPD process for large-volume production.

A transparent dielectric elastomer actuator driven by few-layer-graphene (FLG) electrode was experimentally investigated. The electrodes were made of graphene, which was dispersed in Nmethyl-pyrrolidone. The transparent actuator was fabricated from developed FLG electrodes. The FLG electrode with its sheet resistance of 0.45 kX/sq (80 nm thick) was implemented to mask silicone elastomer. The developed FLG-driven actuator exhibited an optical transparency of over 57% at a wavenumber of 600 nm and produced bending displacement performance ranging from 29 to 946 lm as functions of frequency and voltage. The focus variation was clearly demonstrated under actuation to study its application-feasibility in variable focus lens and various opto-electro-mechanical devices. V C 2013 AIP Publishing LLC. [http://dx.

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